CA1254403A - Boring process and apparatus - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A boring process involves the step suspending a boring bar for boring a hole in a work for pivotal movement in either directions. Then, the work is brought below the boring bar with the axle of said hole being vertical. Thereafter, the boring bar is lowered and eccentrically passed through the hole in the work and slidably and rotatably supported at least at two points thereof axially spaced apart. Then, the boring is effected by the rotation and axial relative movement of the boring bar with respect to the work, with the axis of the boring bar aligned with the axis of the work. Apparatus for carrying out the boring is provided.

Description

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; The present Invention relates to a process and appara-tus for borlng a wor~plece havlng a hole whlch Is to be bored over a relatlve great dlstance In the axlal dlrectlon, for exam-ple, a cyllnder block for an englne havlng a plurallty of bearlng holes concentrlcally formed ~hereln at spaced locatlons for sup-portlng a crankshaf~, or a cyllnder head for an englne havlng a plurallty o~ bearlng holes concentrlcally formed thereln at spaced locatlons for supportlng a cam sha~t.

In borlng such a wor~plece, as dlsclosed In Japanese Utlllty Model PublIcatlon Kokoku No. 114~8/83, It Is a conven-tlonal practlce to support the workplece wlth thffff axls of the hole to be bored belng horIzontal and to ~ove a horIzontally orl-ented borlng bar In a horlzontal dlrectlon to effect the borlng.
However, when the hole to be bored Is relatlvely long In the axlal dlrectlon, the borlng bar Is also correspondlngly long. For thls reason, a deflectlon may be produced In the bor-Ing bar In the portlon between the bearlng portlons due to Its -' Z own welght to cause a so-called skipplng phenomenon and conse-quently, the working accuracy may be adversely affected. There-fore, the speed of rotatlon of the borlng bar must be kept rela-tlve~y low, result~ng In a low worklng rate.

The present Inventlon provldes a borlng process whereln a borlng bar Is rotatlvely drlven about a vertlcal axls ~o e~ect the borlng, so ~hat deflectlon of ~he borlng bar may b0 prevented f to Improve the workIng accuracy, whlle the bearIng structure of I the borln~ bar is slmpllfled and further, the wor~ln~ efflclency Is also Improved.

The present Inventlon also provldes a borlng apparatus most 5UI table for carrylng out such a borlng process.

Accordlng to the present Inventlon there Is provlded a process ~or borln~ a workplece havln~ a plurallty o~ ax~ally spaced holes whlch ar~ to be bored over a relatlvely great dls-tance In the axlal dlrectlon of the workplece, comprlslng the steps of suspendlny for unlversal plvotal movement a borlng bar whlch has a plurailty oF cutters provlded thereon at axlally , 5 spaced posltlons and extendln~ radlally eccentrlcally at one slde ; of the bar, sald cutters belng adapted for borlng a plurallty of holes In a workplece provlded on a common axls at axlally spaced posltlons; brln~lng and locatlng the workplece to a positlon below the borlng bar wlth the axls of sald holes belng vertlcal and transversely off~et from the axls of the borlng bar and then lowerlng sald borlng bar whlle hoi d I ng ~he offset locatlon of the ; bar rela~lve to the holes to pass the borlng bar through the holes In the wor~plece, so as to avold contact of the cutters on ; the bar wlth the holes, slldably and rotatably supportlng the ` 15 borlng bar at least at two polnts thereof axlally spaced apart `, from each other, allgnlng the axls of the borlng bar and the axls of the holes In the workplece by transversely dlsplaclng the workplece relatlve to the borln~ bar; and effectlng borlng of sald holes by provldlng relatlve rotatlon and axlal movement between the borlng bar and the workp I ece ~nd the axls of ~he bor-Ing bar remalnlng allgned wlth the axls of the workplece.
., Thus, accordlng to the present Inventlon, there Is pro-vIded a borlng process comprlsIn~ the steps of suspendlny a bor-Ing bar for borlng a hole In a wor~plec~ for p~votal mov~ment In all dlrectlons, brlnglng the workplece below the borlng bar wlth ~ the hole beln~ vertlr,al and then lowerlng the borlng bar to i, eccentrlcally pass the borIng bar through the hole In the work-~:. plece and slldably and rotatably support the borIng bar at least at two places spaced from each other In the axlal dlrectlon, and effectln~ rotatlon and axlal relatlve movement of the borlng bar wlth respect to the workplece to effect the borlng~

In one embodlment of the present Inventlon the axls of . 3~ the borln~ bar and the axls of the holes In the workplece are allgned before borlng by transversely movln~ the workplece rela-

-2-i tlve to the bar. Sultably ~he allgnlng of the axis of the borlng bar and the axls of the holes In the workplece Is effected whlle the workplece remalns rotatably and sll~ably supported at sald at least two polnts.

In another embodlment of the present Inventlon sald axlal holes In the wor~plece are ~ormed In axlally spaced bearlng : portlons of the workplece, sald borlng bar belng lowered eccen-trlcally through the wor~plece untll each cutter Is brought to a posltlon axlally sllghtly offset from the hole In the respectlve , bearlng por~lon whlch It Is to bore whereafter when the axls of ; the borlng bar and the axls of the hole are allgned, the cutters wlll be In operatlve posltlon ~o bore the holes In the bearlng portlons when relatlve ro~atlon and axlal movement Is provlded 1~ between the borlng bar and the workplece. Sultably the process comprIses eccentrIcally posltlonln3 the borIng bar and the work-plece after the borlng operatlon and ralslng the borlng bar from the holes In the wor~plece In eccentrlc relatlon to avold contact of the cutters wlth the bored holes.

In a stlll further embodlment of the present Inventlon the borlng bar ts supported at one of sald polnts by a support tube In a support member, sald support tube movlng axlally in sald support member durlng axlal Insertlon o~ the borlng bar Into the workplece, sald support tube havlng a released posltlon for loose Insertlvn of the borlng bar Into the hole and an engaged posltlon when the borlng bar bores the holes In the workplece, sald support tube and support member undergolng relatlve angular movement when golng betwesn sald released and engaged posltlons durlng relatlve axlal travel of the borlng bar prlor to the bor-Ing of sald holes. Sultably the process comprlses reslllently and tlghtly engaglng the borlng bar In a slldable and rotatable bearIng at one of sald other polnts at whlch the bar Is slldably and rotatably supported when ~he borlng bar has been passed . 35 throu~h the hole.

: ~ - 3 -The present Inven~lon also provldes an apparatus for borlng a plurallty of axlally spaced holes In a workplece over a relatlve great dlstance In the axlal dlrectlon of the workplece comprlslng a vertlcal post; a tool head rnovably supported on said . ~ post around the clrcumference thereof and Includlng a vertical `~ rotary shaft; a borlng bar havlng an upper end and provlded wlth a plurallty of cutters extendlng radially and eccentrlcally at . one slde of ~he bar at axlally spaced posltlons thereon; a unl~
versal Jolnt connectlng the upper end of lthe borlng bar to the rotary shaft to suspend the borlng bar ~rom the tool head for unlversal plvotal movement; a support Jlg Including at least two bearlng port~ons dlsposed on sald post for slldably and rotatably : supportlng sald borlng bar; and means for supportlng the work-plece for selectlve posltlonlng of the holes In the workplece wlth respect to the borlng bar between eccentrlc and concentrlc posltlons sald support means belng operable to hold the work-plece In the eccentrlc posltlon relatlve to the bar when the bar Is passed through the holes In the workplece In order to avold contact of ~he cutters wlth the holes and to hvld the workplece In the concentrlc posltlon relatlve to the bar durlng the borlng operatlon.

In a partlcular aspect thereof the present Inventlon provldes an apparatus for borlng a hole in a workplece over a relatlve great dlstance In the axlal dlrectlon. comprlslng a v~r-tlcal post; a tool head movably supported on said post and I nG ludlng a vertlcal rotary shaft; a borlng bar havlng an upper end; a unlversal Jolnt connectlng the upper end o~ the borlng bar to the rotary shaft to suspend the borlng bar frvm the tool head 1 30 for unlversal plvotal movement; a support Jlg Includlng at least ! two bearlng portions dlsposed on sald post for slldably and rotatably supportlng sald borlng bar; suppor~ means ~or support-Ing the workplece For selectlve posltlonlng of the hole In the workplece ~Ith respect to the borlng bar between eccentrlc and concentrlc posltlons; a ~enerally regular polygonal support tube fltted on sald borlng bar and havlng an external surface wlth . - 4 ~

plurallty of aplces and a clrcul~rly arcuate sllde surface at each apex; a support member fIxedly mounted on one of sald bear-Ing portlons of sald support Jlg, sald suPport mernber havlng a generally clrcular support hole wlth an Internal dlameter corre--spondlng to that of sald sllde surFace, amd axlally extendlng escape grooves at clrcumferentlally regubar spaced Intervals In the same number as sald sllde surfaces, sald support tube belng insertable Into sald suppor~ member; and ~ulde means between sald support rnember and sald support tube for angularly dlsplaclng sald support tube relatl~e to sald support member to cause each sllde surface facin~ a correspondln~ escape groove to come Into slldlng contact wlth an Inner surface of sald support hole when , the support tube advances a glven dlstance aFter the start of Insertlon thereof Into sald support member.
~ 15 7 Thus, the borlng apparatus of the present Inventlon comprlses a ~ertlcal post; a tool head llftable along the post and Includlng a vertlcal rotary shaft; a borlng bar connected at Its upper end to the rotary shaft of the tool head through a unl-versal Jolnt and suspended from the tool head; a support Jig hav-Ing at least two bearlng portlons and dlsposed on the lower por-tlon of th~ post for slldably and rotatably supportlng the borlng bar; and a workplece support meehanlsm for supportlng the wor~-plece In such a manner to enable the selectlve positlonln~ of the hole In the workplece wlth respect to the borlng ~ar bet~een eccentrlc and concentrlc posltlons.

As descrlbed above, the boring bar Is suspended ~or plvotal movement In all dlrectlons and hence, It Is vertlcally retalned by Its own welght. In thls vertlcal state, the borln~
bar Is slldably and rotatably supported and posltioned concentrl-cally wlth respect to the hole In the workplece to effect the borln~. Therefore, the welght of the borlng bar acts In the axlal dlrectlon thereof to avold the generatlon of a deflectlon In the borln~ bar, thus preventlng a vlbratlon and a sklpplng phenomenon from belng generated due to such a de~lectlon. Thls enables the dlstance between suppor~ posltlons of the borlng bar to be Increased, leadlng to a reduc~d ll~ltatlon for the work-plece and a slmpllfled supportlng structure. In addltlon, slnce the rotatlonal speed can be Increased, the wor~lng efflclency Is enhanced. Furthcr, because the borlng bar Is plvotally movable, the axls of the hole of the workplece can be accurately alIgned wlth the axls of the bor~ng bar to enhance the work I ng accuracy.

In addltlon, wl th the aforesald borlng apparatus, the borlng bar can be plvotally movably supported on the tool head and can be also passed through the hole In the workp I ece to move the wor~plece to a concentrlcal posltlon. The support Jlg Is of extremely slmple construction havlng only at least two bearlng portlons. Accordlngly, It Is posslble to provide a borlng appa-ratus most sultabie for carrylng out a borlng process accordlng to the present Inventlon.

In one embodlment the apparatus comprlses a drlve mechanlsm Includlng a ro~ary drl ve motor llftably dlsposed on sald post, a llft mechanlsm on sald post for llftlng sald drlve mechanlsm on sald post, sald vertlcal rotary shaft belng con-nectable to said rotary drlve motor and detachably connected to sald drlve mechanlsm, a Jlg carrler for supportlng a plurall4y of support Jlgs around sald post, ~eans supportlng sald Jlg carrler for rotatlon about a vertlcal axls of the post, and an Index mechanlsm connected to the Jlg carrler for angularly moving a deslred support Jlg to a posltlon below the borlng bar. Sultably the apparatus compr~ses a pluralIty of sald tool heads arranged around sald post, a head carrler supportlng sald tool heads and 30 dlsposed for rotatlon around sald post, and another Index mecha-nlsm connected to the head carrler to angularly dlsplace a deslred tool head to a posi t I on at sa I d dr I ve mechanlsm. Deslr-ably said support means Includes a movab I e stand I nc I ud I ng a holdlng frame for detachably holdlng a pallet for supportlng and flxlng the workplece and belng movable to a posltlon below the ; borlng bar, and a stop posltlon swltch-over cyllnder posltloned ;
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to restrlct the movement o$ the movable stand In two steps and Includlng a rod for abutting agalnst the movable stand In two positlons, on one of sald posltions the axls of the holes In the workplece belng dlsplaced from the axls of the borlng bar to assume sald eccentrlc posltlon and In the other of sald posltlons the axls of the holes belng allgned wlth the borlng bar to assume sald concen~rlc posltlon ~hereby to enabie the borlng bar to be Inserted through sald holes. Prefera~ly the apparatus comprlses a generally regular polygonal support tube fitted on sald borlng bar and havlng an external surface wlth plurallty of aplces and a clrcularly arcu.ate sllde surface at each apex, and a support mem-ber fIxedly mounted on one of sald bearIng portlons of sald sup-port Jlg, sald support member havlng a generally clrcular support hole wlth an Internal dlameter correspondlng to that of sald sllde surface, and axlally extendlng escape grooves at clrcumfer-entially regular spaced Intervals In the same number as sald sllde surfaces, sald support tube belng Insertable Into sald sup-port member, and gulde means between sa~d support member and sald support tube for angulariy dlsplaclng sald support tube relatlve to sald support member to cause each sllde surface facln3 a cor-respondlng escape ~roove to come Into slIdlng contaot wlth an Inner surface of sald support hole when the support tube advances a glven dlstance after the start of Insertlon thereof Into sald support member.
; 2~
In a partlcular aspect of the present Inventlon there Is provlded an apparatus for borlng a hole in a wor~plece over a relatlve ~re~t dlstance In the axlal dlrectlon, comprlslng a ver-tlcal post; a toD I head movably supported on sald post and 30 Includlng a vertlcal rotary shaft; a borlng bar havlng an upper end; a unlversal Jolnt connectlng the upper end of the borlng bar to th~ rotary shaft to suspend ~he borlng bar from the tool head for unlversal plvotal moYement; a support Jlg Includlng at least two bearln~ portlons dlsposed on sald post for slldably and rotatably, suppor~lng sald borlng bar; and support means for sup-portlng the workplece ~or selectlve posltlonlng of the hole In - 6a ~

~5~(~;3 the workplece wlth respect ~o the borlng bar between eccentrlc and concentrlc posltlons; sald support means Includlng a movable stand Includlng a ho~dlng frame for detachably holdlng a pallet for supportlng and fIxlng the workplece and belng movable to a posltlon below the borlng bar, and stop posltlon swltch-over cyllnder posltloned to restrlct the movement of the movlng stand In two ~teps and Includlng a rod for abuttlng agalnst the movlng stand In two posltlons, In one oF sald posltlons the axls of the hole In the workplece beln~ dlsplaced from the axls of the borlng bar to assume sald eccentrlc posl~lon and In the other of sald posltlons the axls of the hole belng allgned wlth the a~ls of the borlng bar to assume sald concentric posltlon thereby to enable the borlng bar to be Inserted through sald hole.

1~ In another aspect of the present Inventton there Is provlded a process for borlng a wor~plece dlsposed at a worklng statlon located adJacent the lower portlon of a vertlcal suPport post, sald post havlng a substantlally cyllndrlcal conflguratlon and belng provlded wlth a plurallty of worklng tools around the outer perlphery of the post, sald tools beln~ spaced from each other and movable clrcumferentlally of the post such that a deslred one of the tools can be moved to a posltlon above the workplece of the worklng statlon and lowered to bore the work-piece, sald process comprlslng the steps of provldlng the work-plece wlth a pluralIty of holes to be bored on a common axls ataxlally spaced posltlons over a relatlvely lon~ dlstance; vertl-cally suspendlng a borlng bar as sald ~ool for unlversal movement at the worklng statlon, sald borlng bar havlng a plurallty of cutters thereon at axlally spaced posltlons proJectlng In a radlal dlrectlon at one slde o~ the bar; brlnglng and locatlng the workplece ~o a posltlon below the borlng bar wlth the axls of sald holes belng vertlcal and radlalIy oFfset from the axls of the borIng bar and then lowerlng sald borlng bar whlie malntaln~
In~ the offset locatlon of the bar relatlve to the holes to pass the borlng bar through the holes 5n the workplece wlthout contaot of the cutters on the bar wlth the holes, and rotatably support-- 6 ~

~25i~1~

Ing the borlng bar at least at two polnts axlally spaced apart from each other; and dlsplaclng the wor~plece relatlve to the borIng bar to allgn the ax~s of the borIng bar and the axls of the holes In the workplece and effectlng borlng of sald holes whlle rotatlng sald bar around Its axls.

In a stlll further aspect of the present Inventlon there Is provlded an apparatus for borlng a plurallty of axlally spaced holes In a wor~plece over a relatlvely yreat dlstance In the axlal dlrectlon thereo~, sald apparatus comprlsIng a vertlcal support post; a pluralIty of tool heads havlng respectlve axes of rotatlon and movably supported on sald post at clrcumferentlally spaced pvsltlons, sald tool heads belng selectlvely movable to a worklng statlon located adJacent the post and belng capable of ascendlng and descendln~ movements at sald worklng statlon; a pluralIty of borlng bars constltutlng worklng tools vertlcally susp0nded from respectlve toolheads for unlversal movement, sald borlng bars each Includlng a plurallty of cutters thereon at axl-ally spaced posltlons proJectlng radlally at one slde of the bor-Ing bar; a unlversal Jolnt for each borlng bar connectln~ anupper end of the borln~ bar to a vertlcal rotary shaft of thé
tool head to suspend the bar ~or sald unlversal ~ovement; a sup-port Jlg Includlng at least two bearlng portlons dlsposed on sald post at the worklng statlon for sl!da~ly and rotatably supportlng 2~ the borln~ bar at the worklng sta~lon; and support means for sup-porting a wor~plece, whlch has a plurallty of holes to be bored on a co~mon axls and at axlally spaced posltlons over a rela-tlvely great dlstance, for selectlve posltlonlng of the holes In the workplece wlth respect to the borlng bar between eccentrlc and concentrlc posltlons relatlve to the axls of the borlng bar;
sald support means Includlng means for holdlng the workplece In the eccentrlc posltlon relatlve to the bar, when the bar Is passed through the holes in the workplece at sald worklng sta-tlon, In order to avold contact of the cutters w5th the holes and for holdlng the workplece In the concen~rlc posltlon relatl~e to the bar durlng the borln~ operatlon.

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~ ~Z5 4~4 The present Inventlon will be further l.,llustrated by way of a preferred embodlment wlth reference ~o the accompanylng drawln~s, In whlch:-Flg. 1 Is a perspectl Ye vI ew of a borlng apparatusaccordlng to one embodlment of the present Inventlon;

Flg. 2 Is a vertlcal sectlonal vlew of the borlng appa-ratus of Fl~. 1;
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Flg. 3 Is an enlar~ed sectlonal vlew taken along llne Ill- ~ In Flg. 2;

Fig. 4 Is an enlar~ed sectlonal vlew taken along llne V-IV In Fl~. 2, Fl~. 5 Is an enlar~ed vlew In vertlcal sectlon of detalls at the completlon of borlng;

Fl~. 6 Is an enlar~ed sectlonal vlew taken alon~ llne Vl-VI In Fl~ 2 F39. 7 Is a vlew taken along llne VII-VII In Flg. 2;

Flg. 8 Is a sectlonal vlew at the start of Insertlon, taken along llne V_ I-VIII In Flg. 5;

Fl~. 8A Is an enlarged vlew of the sectlon enclrcled by clrcular broken llne VIIIA In F13. 8;

Flg. 9 Is a sectlona~ v~ew taken along llne IX-IX In Flg. 5;

Flg. 9A Is an enl~rged vlew of the sectlon enclrcled by clrcular bro~en llne ~ In Flg. 9;

~. - 6d 3LZ54~

`~ ~Ig. 10 Is a sec~lonal vlew ~aken along llne X-X In i Flg. 8 wlth a b~rln~ bar omltted;
.
~ Fl~. 11 Is an enlarged vlew ta~en along IIne ~-XI In 1~ 6 Flg- ~;

Flg. 12 Is an enlarsed vlew taken alon~ llne XII-XII In ~ Flg. 5;

j 10 Flg. 13 Is an enlarged ~iew taken along llne Xl ! 1 In Flg. 5;

Flg. 14 Is a sectlonal vlew taken along ilne XIV-XIV In Flg. 12 wl~h the borlng bar omltted, ' 15 Flg. 15 Is an enlarged vlew l~ vertlcal sectlon of ` detalls for Illustratlng the supPort of the lower end of the bor-`'~ Ing bar;

I O Fl~. 16 ~s a sec~lonal vlew taken a~ong llne XVI-XVI In Flg. 15;

Flg. 17 Is a vertlcal sectl~nal vlew of detalls for Illustratlng the stats of borlng bar Inserted In the bearlng hole 2~ In the workplece on an enlarged scale; and Fl~. 18 is an enlarged vlew In vertical sectlon of detalis correspondlng to Flg. 17, wlth the axls of the borlng bar ~ belng ali~ned wlth the axls of the bearlng hole In the wor~plece.
; 30 One embodlment of the present Inventlon wlli nvw be descrlbed wl~h re~erence to the drawlngs. Re~errlng flrst to ; Flg.s 1 and 2, thereln Is shown a borlng apparatus 1 whlch com-, prlses an uprlght post 3 rlslng on a base plate ~, a drlve mecha-s 35 nlsm 4 llftably dlsposed lateral~y of the post 3 at a worklng statlon S on the base plate 2, a llft mechanlsm ~ For llftably 6e ~

~25q~6~

moYin~ the drlve mechanlsm 4, a plurall~y of. ~or example, four tool heads 6 each adapted to be detacha~ly flxed on the lower portlon of the drlve mechanlsm 4 by the selectlve swltch-over thereof, and a borlng bar 7 detachably connected at Its upper end to each of the tool heads 6 to extend downwardly and be used as a bar-lIke rotary worklng tool. The borlng apparatus 1 also Includes a plurallty of, for examp~e, four support Jl~s 8 each adapted ~o be fIxed on ~he lower portlon of the post 3 by the se-lectlve swltch-over thereof at a locatlon correspondlng to the borlng bar 7, I.e., a locatlon at the worklng statlon S, a work support mechanlsm 9 for supportlng and posltlonlng a wor~plece W
whlch has been transferred or conveyed to the worklng statlon S, such as a cyllnder head havlng flve bearlng bores concentrlcally spaced from one another for a cam shaft, and a transfer or con-. 15 veylng mechanlsm 10 for the transfer-ln and the transfer-out of the workplece W to and $rom the workln~ statlon S.

The drIve mechanlsm 4 Includes a llft rest or stand 12 horlzontally dlsposed above the workln~ statlon S to extend radl-ally and ~utwardly from the post 3, and a rotary drlve motor 13 ~, carrled and flxed on the upper surface of the llft ~ ., '. :

., ' .

A

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rest stand 12. The rotary dri~e motor 13 is disposed with its output shaft 14 directed vertically, the output shaft 14 rotatably passing through the lift stand or rest 12 to have its lower end downwardly pro;ected from the lower surface of the lift rest 12. The lower end of the outputs shaft 14 has a structure which enables the splined connection thereof with a rotary shaft 5~ o the tool head 6 by fi-tting the rotary shaft 54 to the lower end from below. The rotary drive motor 13 also includes a given-position stop mechanism such that cutters 63 of the boring bar 7 may always be accurately oriented in an opposite direction to the post 3.

Referring also to Fig. 3, the lift mechanism 5 includes a threaded rod 15 threadedly connected to the lift stand 12 of the drive mechanism ~ to extend vertically and a feed motor 16 for rotatively driving the threaded rod 15. The rod 15 is dis-posed to extend vertically along the outer side surface of the post 3 and threadedly fitted in a threaded bore 17 in the lift stand 12. The threaded rod 15 is also rotatably journaled at its upper and lower ends by the post 3, and the feed motor 16 is connected to the upper end of the threaded rod 15 and fixed to the upper portion of the post 3. Moreover, the feed motor 16 is reversibly rotatable in opposite directions.

On the opposite sides of the threaded rod 15, a pair of vertically extending guide rails 18 are securely mounted on the outer side surface of the post 3, so that the lift ~tand 12 is fitted on the guide rails 18. Thus, the lift stand 12 inhibits the angular displacement of the threaded rod 15 about the axis thereof and moves up and down along both the guide rails 18 in accordance with the rotation of the threaded rod 15 by the activation of the motor 16.

A paiL of vertically extending balance cylinders 19 are fixedly mounted on the upper portion of the post 3 and disposed on diametrically opposite sides of the lift stand 12, and each of ~25M1~3 the balance cylinders l~ has a rod slidably fitted there1n and secured to the lift stand 12. This enables the lift stand 12 to be moved up and down wlth its horizontal position maintained.

Referring also to Fig. 4, the individual tool heads 6 are disposed at circumferencially spaced intervals of 90 around the post 3 to provide for the co.nnection and holding oE different boring bars 7 so as to accommodate the variation in type of work pleces W. The tool heads 6 are carried out on the head carrier 22, respectively, so that movement of the head carrier Z2 around the post 3 enables any tool head 6 and boring bar 7 to be brought into position at the worklng station S and thus at the drive mechanism 4.

A downwardly opened upper guide member 23 having a U-shaped cross section is securely mounted on the upper and outer side surface of the post 3 to form an arc with the drive mechanism 4 about the center of the post 3. Also below and at a spaced dlstance from the upper guide member 23, an upwardly opened lower guide member 24 having a U-shaped cross section is fixedly mounted on the outer side surface of the post 3 by a bracket 25 to form an arc corresponding to that of the upper guide member 23.

On the other hand, the lift stand 12 of the drive mechanism 4 has an upper guide groove 26 and a lower guide groove 27 therein, the former being connected with the upper guide member 23 and the latter with the lower guide member 24 when the lift stand or rest 12 assumes a given uppermost limited position.
Both the guide groove 26 and 27 are curved with the same radius of curvature as that of the upper and lower guide members 23 and 24.

Each head carrier 22 is curved in an arc with a radius of curvature corresponding to that of the upper and lower guide member 23 and Z4 and disposed between the upper and lower guide ~254~03 members 23 and 2~. Connecting pieces 28 curved in an arc li~e the head carrier 22 are disposed between both the head carriers 22, each head carrier 22 being connected to the adjacent connecting piece 28.

More specifically, a connecting arm 29 is mounted at the curcumferentially opposite ends of the head carrier 22 to project outwardly and arm 29, has a connecting pin 30 embedded in the fore end thereof~ On the other hand, a connecting jaw 31 is projectedly mounted on the outer surface of the connecting piece 28 above the connecting arms 29 over the entire circumference, so that the connecting pins 30 may be inserted into connecting holes 32 in the opposite ends of the connecting jaw 31 to provlde the interconnection between each head carrier 22 and each connecting piece 28.
Sector gears 33 and 34 are securely mounted on the upper portion of each head carrier 22 and on the upper portion of each connectlng piece 28, respectively, and they ~5 ~l25~3 C ~ c~~; ~J e ~1 wbf~r~~LtUub~ c~n~titute an internal gear 35.
A plur~lity oP roller~ 36 and 3~ are supported on the upper portion of th~ head carrier 22 and on the upper portion of the connectin~ piece 23, reclpec-tively and are rollable on the upp~r guide member 23 and ~n the upper guide groove 26. Further, a plurallty o~ rollsr 38 and 39 and a plurality of roller~ 40 and 41 are also ~upport~d on the lower portion of the head carrier 22 and on the lo~er portion o~ the connecting piece 28, re~pectiv~ly, th~ for~er rollers being rollable on the lower ~uide member 24 and in the lower guid~ groove 2~, and th~ latter rollers being rollable on the outer and upper ed~e of the lower guide member 24 and in the lower guide groove 2~. Thi~ snable~
each head carrier 22 and each connecting piece 28 to be guided and moved in the interconnected ~tate betwe~n thR
upper and lower guide member~ 23 and 24 and between the upper and lower guide groove~ 26 and 2~, i.e., rotated around the post 3.
An index mechanism 42 ls provided for the purpo~e of rotating each head earrler 22 and connecting piece 2~ in this manner to bring any head carrier 22 and thus tool head 6 into the po~ition at the drive mechani~m 4. The index meehanism 42 is compri~ed of an index ~otor 43, a gear box 44 containing a gear train ~not ~hown) ~or decel~rationaly tran~mitting the driving force fro~ the index motor 43, and a driv~ gear 46 fixed on the output shaft 45 of the gear box ;~ ~heSl~
44 and ~s~a~ wlth the int~rnal gear 35. The gear ~ox 44 is fixed on the upper portion of the post 3, and the index ~otor ~3 is fixed and 3upported on the upper portion o~ the ~25~86B3 gear box 44. The output shaft 45 projects downwardly out of the gear box 4 and has the drive gear 46 fixed at the lower end thereof.

With such index mechanism 42, the actuation of the index motor 43 enables the internal gear 35, i.e., the head carrier 22 and the connecting piece 28 to be rotated, thereby bringing a desired head carrier 22 in-to a position below the driYe mechanism ~.

Referrin~ also to Fig. 5, the tool head 6 is supported on the head carrier 22 for upward relative movement. More specifically, tne head carrler 22 is integrally provided with a support arm ~7 pro;ected therefrom below the connecting arm 29 and a support pin 48 rises on each connecting arm 29 and a support pin 49 rises on each support arm 47. On the other hand, upper and lower arms 50 and 51 pro~ect from the tool head 6 and are restable on each connecting arm 29 and each support arm 47, respectively. Through holes 52 and 53 through which the support pins 48 and 49 can be respectively inserted are made in the arms 50 and 51, respectivelyO Moreover, the thickness of each the arms 50 and 51 is smaller than the length of the support pins 48 and 49, so that the tool head 6 can be relatively moved upwardly with respect to the head carrier 22 to move each of the arms 50 and 51 upwardly away from the cGnnecting arm 29 and support arm 47 w~th the support pins 48 and 4g remaining lnserted in the through holes 52 and 53 respectively.

A rotary shaft 54 having a vertical axis is journaled on the tool head 6 for rotation about the axis and has upper and lower opposite ends pro;ecting from the tool head 6. Moreoyer, the length of rotary shaft 54 pro;ecting upwardly from the tool head 6 is such that the upper end of the rotary shaft 54 will not reach the lower end of the output shaft 14 in the drive mechanism

4 when the arms 50 and 51 rest on the connecting arm 29 and support arm 47 respectively, but will be splinedly connected to ~2s~a~3 the lower end of the output shaft 14 when the tool head 6 is moved up and fixed to the drive mechanism 4.

A plurality, for example, four locking members 55 are secured on the upper surface of the tool head 6 in order to fix the tool head 6 to the drive mechanism 4. The locking members 55 each have an engaging groove 56 substantially T-shaped in cross section, and are fixedly disposed with their engaging grooves 56 extending along the circumference about the rotational center of the tool head 6. Four clamp cylind~rs 57 are fixedly supported : on the upper surface of the llft stand 12 in the drive mechanism 4 to correspond to the respective locking members 55. The clamp cylinders 57 are each disposed with its axis vertical and each has a rod 58 moveably passed through the lift stand 12 to project downwardly from the lift stand 12, which rod 58 has a substan-tially T-shaped engaging portion 59 provided at its lower end and capable of engaging the engaging groove 56 in each the locking members 55.

With each clamp cylinder 57 extended, the ~ngaging portion 59 of each rod 58 is in a position to be engageable with the locking member 55 on the tool head 6 resting on the connect-~ng jaw 31 and the support arm 47, and when the clamp rylinders 57 are retracted, the engaging portion 59 is engaged with the engaging member 55, thereby causing the tool head 6 to be pulled up .

A plurality, for example, four positioning pins 60 are mounted on the upper surface of the tool head 6, while four fitting tubes 61 into ~hich the respeckive positioning pins 60 can be fitted are secured to the lower surface o-f the lift stand 12. When the tool head 6 is pulled up by the clamp cyli.nders 57, each pos.itioning pin 60 is fitted into the respective fitting tube 61, thereby providing the positioning of the tool head 6.
Moreover, end positioning pin 60 is provided with an upwardly-facing stepped portion on the outer surface thereof, so that the ~5~(~

pulling up of the tool head 6 by the operatlon of the clamp cylinders 57 causes the stepped portion to abut agalnst the lower surface of the fitting tube ~l, thereby preventing further pulling-up act~on and permitting the tool head 6 to be fixed to the lift stand 12.

A boring bar 7 is connected at its upper end to the lower end of the rotary shaft 54 in the tool head 6 through a universal joint 62. Therefore, the boring bar 7 is suspended from the tool head 6 for swinging movement in all directions through 360C in a horizontal plane. The boring bar 7 has cutters 63 fixedly mounted on one side surface thereof at spaced locatlons each corresponding to that between the ad;acent bearing bores ll in work pieces W to be bored.

Referring to Figs. 6 and 7, four support jigs are arranged on -the lower portion of the post 3 at angularly spaced intervals of 90 around the post 3 for slidably and rotatably supporting boring bars 7 of different type, respectively. The support jigs ~ are carri~d on a cylindrical jig carrier 64 sur-rounding the post ~, so that the angular displacement of the jig : carrier 64 about its vertical axis enables a desired ~ig 8 to be brought to the working station S.

An upper downwardly opened guide rail 65 of U-shaped cross section is fixed on the outer side surface at the lower portion of the post 3 along a phantom circumference about the center of the post 3 and a lower upwardly opened guide rail 66 is fixed at a location downwardly spaced ~rom the upper guide rail 65 and along a phantom circumference corresponding to that of the upper guide rail 65.

The jig carrier 64 ls disposed between the upper and lower guide rails 65 and 66. A plurality of rollers 67 are supported at spaced locations on the upper portion of the ~ig carrier 64 to roll within the lower guide rail 66, and a ~2~ 3 plurality of rollers 141 are supported ~t spaced locations to roll on the outer and upper edge of the lower guid~ rail 66.
Therefore, the ~ig carrier 64 can be ~uided on the upper and lower guide rai.ls 65 and 66 to rotate about the vertical axis.

For the purpose of rotationally operating the ~ig carrier 64, an index mechanism 69 is disposed on the lower portion of the post 3. The index mechanism 69 includes an index motor 70, a gear box 71 containlng a gear train (not shown) for decelerationaly transmitting the driving force from the index motor 70, a dr.ive gear 72, and a gear train 73 for transmitting a driving force from the gear box 71 to the drive gear 72. The gear box 71 is secured to the lower portion of the post 3, and the index motor 70 is fixedly mounted on the lower portion of the gear box 71.

An internal gear 74 is securely mounted on the lower portion of the ~ig carrier 64, so that the drive gear 72 is in mesh with the internal gear 74. Therefore, the actuation of the index motor 70 causes the drive gear 72 to rotate the internal gear 74 and thus jig carrier 64.

The support jig 8 is comprises of a generally rectangular ~ig body 75, two bearing portions 76 and 77 inte-grally projecting at the upper and lower opposite ends of the ~igbody 75, and a bearing member 82 mounted on the jig body 75 between the bearing portions 76 and 77.

Referring to Figs. 8, 9 and 10, the upper bearing portion 76 has a generally cylindrical support member 80 securely mounted thereon and having a vertically extending support hole 78. A support tube 145 is fitted over the upper portion of the boring bar 7 through a bearing 150 and is removably supported by the support member 80.

The contour configuration in cross section o:E the ~3 support tube 145 is basically regularly polygonal, for example, regularly dodecagonal with a circular arc-shaped slide surface 146 at each apex as shown in Fig~ 8A. In other words, the outer surface of the support tube 1~5 is shaped in an arc of a circle in a range of an extremely small central angle with a plurality of slide surfaces 146 arranged at curcumferentially regular intervals being interconnected by a flat surface 147.

The support hole 78 in the support member 80 is shaped basically as a circle with an internal diameter corresponding to the contour configuration of the circular arc-shaped slide surface 145 and it has the same number of axially extending escape grooves 148 as the slide surfaces at curcumferentially reyular intervals on its inner surface.

The support tube 145 is inserted into the support hnle 78 i~ the support member 80 when the boring bar 7 advances, i.e., moves down. At the start of insertion of the support tube 145, the s~ide surface 146 of the support tube 145 is iQ a position opposed to the escape groove 148 as shown in Figs. 8 and 8A, and while the support tube 145 moves down by a given distance~ 1 from the start of insertion thereof, it is an~ularly displaced by the action of the guide mechanism 149, so that the slide surface 146 comes into slide contact with the inner surface of the support hole 78, as shown in Figs. g and 9A.
The guide mechanism 149 is constituted by a pin 151 pro~ecting from the outer side surfacP of the support tube 145, and a guide groove 15~ provided in the inner surface of the support hole 78 to guide the pin 151 slidably fitted therein.
The pin 151 is mounted on the outer surface of the lower portion of the support tube 145 and projects outwardly from one of the flat surfaces 147. On the other hand, the guide groove 152 is provided over the entire length of the support hole 78 and consists of a first straight line portion 153, an inclined ~25~4~3 portion 154 and a second straight line portion 155, which are connected in succession. The first straight line portion 153 ex-tends over a relatively short distance~ 2 along the axis of the support hole 78 between two escape grooves 148. The inclined portion 154 extends over a distance (~ 1-~ 2) from the lower end of the first straight line portion 153 at an inclination escape groove 148. The second straight line portion 155 0xtends on one escape groove 14~.

10With such gulde mechanism 149, when the support tube 145 is moved down the distance 1 after being inserted into the support hole 78 with each slide surface 146 aligned with the respective escape groove 1~8, it is angularly displaced through half a central angle formed by two escape grooves 148 as the pin 15151 is guided in the inclined portion 154 to assume a state as shown in Figs. 9 and 9A. This state corresponds to a position to initiate the working of a work piece W by the boring bar 7, and when the pin 151 is moved down along the second straight line portion 155 into a position P shown by a slant line in Fig. 10, the working is completed.

It is to be noted that at the start of insertion of the support tube 145 into the support hole 78, each slide surface 146 should be in a position opposed to each escape groove 148, and for maintaining such position, for example, a pair of torsion bars 156 may be provided between the tool head 6 and the support tube 145. The torsion bars 156 allow each slide surface 146 to return to the position opposed to each escape groove 148 when the support tube 145 is moved up out of the support hole 78.

Referring to Figs~ 11 to 14, the bearing ~ember 82 is secured to the ~ig body 75 by a bolt 160 and has a through hole 161 coaxial to the support hole 78, into which is forced a cylindrical inner sleeve 162 having a support hole 83 capable of receiving a boring bar 7 inserted thereln.

~;2~ii~L~3 Three annular grooves 163, 164 and 165 are provided at spaced intervals in the inner surface of the through hole 151, and passage holes 166, 167 and 168 are provlded in the bearing member 82 to communicate with the respective corresponding annular grooves 163, 164 and 165. Oil feed pipes 169, 170 and 171 for passage of a cutting oil are also cormected to the re-spective correspondi.ng passage holes 166, 167 and 168.

A passage 172, through which each cutter 63 of boring bar 7 is passed, is made in the inner surface of the support hole 83 over its entlre axial length.

At a locatlon facing the lowermost annular groove 163, a recess 173 is provided in the inner surface of the support hole 83 in the inner sleeve 162 at a point displaced from the passage 172 and recess 173 is a crescent-shaped in cross section to become shallower in the curcumferentially opposite directions, and an oil feed passage 174 connecting the recess 173 with the annular grvove 163 is made in the inner sleeve 162.

In addition, at a location facing the middle annular groove 164, an oil feed passage 175 is provided in the inner sl~eve 162 to connect the middle annular groove 164 with the passage 172. At a location facing the oil feed passage 175, the fore side of the passage 172 in the direction 176 of rotation of the boring bar 7 is cut out in the rotational direction 176 to provide a notch 177 which becomes shallower in the rota-tional direction 176.

E'urther, at a location facing the uppermost annular groove 165, a recess 178 having a configuration similar to that of the recess 173 is provided in the inner surface of the support hole 83 at a point displaced from the recess 173, and an oil feed passage 179 is provided in the inner sleeve 162 to provide the connection between the recess 178 and the annular ~roove 165.

~2~C 13 In this manner, a cutting oil supplied through the individual oil feed pipes 169, 179 and 171 is passed into the recesses 173 and 178 as well as into the passage 172 and the notch 177 and the cutting oil enters the space between the outer surface of the boring bar 7 and the inner surface of the support hole 83 as the boring bar 7 is rotated, so that the boring bar 7 is supported by the inner sleeve 162 under the action of the cutting oil.

Referring to Figs. 15 and 16, the lowermost bearing portion 77 has a through hole 180 therein coaxial to the bearing member 82, so that a ~enerally cylindrical rotary tube 81 is rotatably supported in the through hole 180 through a bearing 181. The rotary tube 81 receives the lower end of the removably inserted boring bar 7, and a positioning mechanism 182 is pro-vided between -the boring bar 7 and the rotary tube 81 for accu-rately positioning the boring bar within the rotary tube 81.

The positioning mechanism 182 is constituted by a groove 184 provided axially in the inner surface of the support hole 79 in the rotary tube 81 over its entire length, and an urging piece 185 resiliently biased into sliding contact with the bottom of the groove 184 and supported at the lower end of the boring bar 7.

A generally cylindrical support member 186 is fixedly mounted on the lower end of the boring bar 7 by a bolt 187 and a key 188 and member 186 has an axially extending slit 189 opposed to the groove 184.

The urging piece 185 is slidably fitted in the slit 189 and rotatably supported at the lower end of the support member 186 by a support shaft 190 perpendicular to the axis of the boring bar 7. Furthermore, a spring 191 is compressively mounted between the inner side surface of the support member 1~6 opposite the slit 189 and the urging piece 185, so that the spring force of the spring 191 causes the urging piece 1~5 to be resiliently biased with one end thereof projecting outwardly from the slit 189. The outer surface at one end of the urging piece 185 is formed with a flat urging surface 192 adapted to come into slid-ing contact with the bottom of the groove 184. Further, on theside opposite the slit 18g, a relatively short restricting slit 194 is provided in the lower end of the support member 186 and formed with a downwardly facing restricting surface lg3. The other end of the urging piece 185 has an abutm~nt surface 195 adapted to abut against the restricting surface 193 and is slidably fitted in the restricting slit 194. Therefore, the amount of urging piece 185 projected from the slit 189 is restricted before the abutment surface 195 abuts against the restricting surface 194.

With such positloning mechanism 182, when the boring bar 7 is inserted into the rotary tube 81, the urging surface 192 of the urging piece 185 resiliently abuts aga.inst the bottom of the groove 184, so that the boring bar 7 is urged away from the groove 184 and necessarily forced into a close contact with the inner surface of the support hole 79 on the side opposite the groove 184, whereby the position of the axial center of the boring bar 7 is always steadily maintained.

The support jig 8 is supported on the ~ig carrier 64 for movement toward and away from the jlg carrier 64 within a restricted range.

More particularly, the jig body 75 of the support jig 8 includes a pair of upper support projections 84 and a pair of lower support pro;ections 85, which are mounted on the side opposite the baring portions 76 and 77. Downwardly bent stoppers 86 and 87 are mounted on the upper and lower pro~ections 8~ and 85, respectively. A pair of upper holding cylinders 88 and a pair of lower holding cylinders 89 are arranged on the jig carrier 64 at curcumferentially spaced intervals of 90 to mate ~25~

with both the upper support projections 84 and the lower support projections 85, respectively. Each of the holding cylinders 88 and 89 has an axis parallel to one diametrical line of the jig carrier 64 and is fixed to pass through the jig carrier 64.
Respective ones of the pairs of the holding cylinders 88 and 89 have upwardly extending protrusions go and 91 mounted on the upper portions of their projected ends for receiving the lower surfaces of the upper end and lower support proiection 84 and 85 thereon, respectively. Further~ urging pins g2 and 93 pro;ect from the projected ends of both the holding cylinders 88 and 89, respectively. The urging pins 92 and 93 are biased by springs 94 and 95 contained within the corresponding holding cylinders 88 - and 89, respectively Wlth such arrangement, the support ~ig 8 is urged by the urging pins 92 and 93 with the upper and lower support pro~ections 84 and 85 placed on the protrusions 90 and 91 on the side of the jig carrier 64 and is supported on the jig carrier 64 with the stoppers 86 and 87 abutting agains$ the corresponding protrusions 9o and 91. If the jig carrier 8 is brought into the working station S in such state, then the axes of the support holes 78, 83 and 79 in the support jig 8 are of the axis of the boring bar 7 located above them, and for the boring, it ~s necessary to move and fix the support jig 8 closer to the jig ~arrier 64.
When the support jig 8 is positioned a-t the working station S, a jig clamp cylinder 96 and a jig clamp cylinder 97 are arranged on the side portion of the post 3 at the upper and lower portions of the jig body 75, respectively. The jig clamp cylinders 96 and 97 each have a rod 98 and 99 provided therein and extending outwardly along one diametrical line of the ~ig carrier 64 with the leading ends of the rods g8 and 99 connected to one of the ends of the clamp members 100 and 101, respec-35 tively. Each of the clamp members 100 and 101 is supported on the post 3 with its middle portion as a fulcrum and is pivotally movable about the horizontal axis with the expanding or contract-ing operation of the jig clamp cylinders 96 and 97.
The jig body 75 of the support jig 8 is integrally provided with an L-shaped bent locking pro~ection 102 engageable by the other end of the upper clamp member 100, and an L-shaped bent projection 103 engageable by the other end of the lower clamp member 101.

Four knock pins 105 each having a restricting stepped portion 104 facing outwardly are projectedly mounted on the side portion of the post 3 to face the working station S, and four positioning holes 106 are perforated in the jig body 75 to correspond to the knock pins 105, respectively.

In a section at the working station S, a bellows-like cover 107 is mounted over the threaded rod 15 to extend between $he lower portion of the post 3 and the lower portion of the lift stand 12 of the drive mechanism 4. Therefore, the threaded rod 15 is always covered, regardless of the upward or downward movement of the drive mechanism 4.

The transfer mechanism 10 is comprised of a pallet guide rail 110 horizontally disposed on the side of the post 3 opposite the working station S, and a pallet 111 guided on the guide rail 110 with a working plece W supported and fixed thereon. The pallet guide rail 110 is constituted of an upper guide portions 114 consisting of a pair of opposed guide plates 112 and a plurality of guide rollers 113 arranged between the guide plates 112, and a lower guide portion 117 consisting of a pair of opposed guide plates 115 and a plurality of guide rollers 116 arranged between the guide plates 115, the upper and lower guide portions being interconnected by a connecting member 118 and oriented horizontally except in the section at the working station S.

The pallet 111 is formed as a flat plate, and is guided on the upper and lower guide portions 114 and 117 of the pallet guide rail 110 and thus transferr~d or conveyed to or from a position at the working station S. The pallet 111 is provided with a plurality of positioning pins 119 adapted to be fitted into a work piece w, upper and lower clamp members 120 and 121 adapted to engage the working piece W for fixing it, and an abutment pin 122 adapted to abut against the work piece W. Upon the fitting of the clamp member 120 and 121 to the work piece W
with the positioning pins 119 fitted into the work piece w and the work piece W abutting against the abutment pins 122, the work piece W is fixed on the pallet 111 with bearing hole 11 being vertical.

The work support mechanism 9 is disposed in place at the working station S on the side opposite the post 3. The work support mechanism g includes a moving stand 125 movable in a horizontal direction perpendicular to the transfer mechanism 10, an urging cylinder 126 for horizontally driving the moving stand 125, a stop position switch-over cylinder 127 adapted to abut against the moving stand 125 for restricting the horizontal movement of the moving stand 125 in two steps, a reverse motor 28 fixed to the moving stand 125, and a pallet holding frame 130 flxed on the leading end of an output shaft 129 of the reverse motor 128.

The moving stand 125 is movable along a pair of guide bars 131 fixedly mounted on the base plate 2 in a horizontal direction perpendicular to the transfer mechanism 10, and a rod 132 o~ the urging cylinder 126 is connected to the moving stand 125. The urging cylinder 126 is fixed at the end of the base plate 2 on the side opposite the post 3 with respect to the working station S, so that its expanding or contracting operation causes the moving stand 125 to be moved toward or away from the working station S.

A stop position switch-over cylinder 127 is opposed to the moving stand 125 at a location near the working station S, and a rod cylinder 127 can switch over the stop position of the moving stand 125 depending on whether the rod is in the extended or retracted states. In other words, when the moving stand 125 is allowed to abut against the extended rod 133, and when the moving stand 125 is brought into abutment against the retracted rod 133, the stop position of the moving stand 125 is switched over.

The output shaft 129 of the reverse motor 128 is rotatably passed through the moving stand 125 and it pro~ects toward the working station S, a pallet holding frame 130 being fixed to the leading end of the output shaft 129. The pallet holding frame 130 is generally formed as a flat plate and has a guide grooves 134 and 135 provlded at the upper and lower oppo-site ends thereof to correspond to the upper and lower guide portions 114 and 117, respectively. Further, a pair of clamp cylinders 136 are arranged on the pallet holding frame 130 and adapted to abut against the pallet 111 for fixing it so that by expanding the clamp cylinders 136 when the pallet lll fitted in the guide grooves 134 and 135, the pallet lll is supported and fixed on the pallet holding frame 130.

With such work support mechanism 9, a work piece W
conveyed by the transfer mechanism lO can be moved to the working station S in two steps and supported. More specifically, upon the expansion of the urging cylinder 126 in the expanded state of the stop position switch-over cylinder 127, the work piece W is brought in a direction opposite to the post 3 into a position of alignment with the axis of the bearing hole ll slightly displaced from the boring bar 7 and then, the urging cylinder 126 is expanded in the contracted state of the stop position switch-over cylinder 127, whereby the work piece w can be moved -to a posit1on with the axis of the bearing hole 11 aligned wlth the bor1ng bar 7 and thus fixedly supported.

A pair of guide posts 138 having a fitting hole 137 at the fore end thereof are mounted on and pro;ect from the pallet 111 toward the post 3 to guide the movement of th~ work piece W
to the posltion in which the axis of the bearing hole 11 is aligned with the boring bar 7. A positioning pin 140 is pro~ectedly mounted on the jig body 75 of the support jig 8 and has at its fore end a fitting projection 139 fittable in the fitting hole 137. In addition, a plurality of positioning holes 142 are formed in that surface of the work piece W held by the pallet 111 which is opposed to the support ~ig 8, while a plurality of positioning pins 143 are pro~ectedly mounted on the jig body 75 in the support jig 8 and adapted to be fitted into the positioning holes 142, respectively.

Description will now be made of the operation of this embodiment. A work piece W is transported by the transfer mechanism 10 to a position at the working station S. Thereupon, the pallet 111 supporting the working piece W is fitted into both guide grooves 134 and 135 of the pallet holding frame 130. In 2~ this state, the clamp cylinder 136 is operated to expand, thereby causing the pallet 111 to be fixed to the pallet folding frame 130. Then, the urging cylinder 126 is operated to expand with the stop position switch-over cylinder 127 remaining expanded, so that the moving stand 125 is moved un-til it abuts against the rod 133 of the stop position switch-over cylinder 127, whereby the work piece W is passed to a position with the axis of the bearing hole 11 slightly displaced from the boring bar 7 on the side opposite the post 3 rather than being just below the boring bar 7.

In this state of work piece W, the feed motor 16 of the lift mechanism 5 ls actuated to rotatively drive the threaded rod 15, thereby lowering the drive mechanism 4, the tool head 6 and the boring bar 7. In this case, the axis of the bearing hole 11 in the work piece W is displaced on the order of several mm from the boring bar 7, and the boring bar 7 is at rest in a fixed - 2~ -~;4~133 position with each cutter 6~ sorrectly oriented in a direction opposite the post 3, so that the boring bar 7 can be lnserted throu~h the bearing hole 11 without any interference of the cutters 63 with the bearing hole 11~

At this lowering, the boring bar 7 is concentrically inserted into the support holes 7~, 83 and 79 in the support jig 8, and when the support tube 145 fitted over the upper portion of the boring bar 7 is inserted into the support hole 78, it is inserted into the support hole 78 while being slightly angularly displaced by the actlon of the guide mechanism 149. Thus, the support tube 145 starts to be inserted in the state with the slide surface 146 thereof opposed to the escapa groove 148. In this state, a space is produced between the support tube 145 and the support hole 78 as shown in Figs. 8 and 8A to ensure that the insertion ls extremely easily conducted, while even if chip and cutting oil are present in the space between the support tube 145 and the support hole 78, they may be discharged from the space and thus, scuffing will not be produced.

When the support tube 145 i5 lowered by the dlstance from the start of inserting, the slide surface 146 is in slide contact with the inner surface of the support hole 78 as shown in Figs. 9 and 9A, and in this state, the support tube 145 is concentrically supported in the support hole 78.

On the other hand, when the lower end of the boring bar 7 is inserted into the support hole 79, the urging piece 185 is slidably fitted in the groove 184, and the operation of tAe positioning mechanism 182 including the urging piece 185 causes the lower end of the boring bar 7 to be lowered while being in close contact with the inner surface of the support hole 79 on the side opposite the groove 184. conse~uently, regardless of whether the internal diameter of the support hole 79 is larger 3~ than the contour of the boring bar 7, with an allowance included therein, the axial center of the lower end of the boring bar 7 is ~;~5~3 always in the same position with respect to the support hole 79.

In the state of the support tube 145 slightly displaced angularly and concentri~ally held in the support hole 78, the i.e., when the pin 151 of the support tube 145 has reached the upper end of the second straight line portion 155 in the guide groove 152, each cutter 63 of the boring bar 7 is above the corresponding bearing hole 11 as shown in ~ig. 17, and ln this state, the axis of each bearing hole 11 rema~ns dlsplaced from the axis of the boring bar 7.
Then, the stop position switch-over cylinder 127 is operated to contract, while the urging cylinder 126 is operated to expand again. This enables the moving stand 125 to advance by an amount corresponding to the retraction of the rod 133 of the stop position switch-over cylinder 127, thereby causing the work piece W supported on the pallet 111 fixed to the pallet holdlng frame 130 to be moved several mm toward the post 3. Thus, the axis of the bearing hole 11 in the work piece W is aligned with the axis of the boring bar 7, as shown in Fig. 18. Moreover, in this case, th~ positioning pin 143 of the support jig 8 is fitted in the positioning hole 142 in the wor~ piece W to providP the positioning of the work piece W.

Thereafter, the boring bar 7 is lowered by the lift mechanism 5 while being ro-tated by the drive mechanism 4, whereby the boring of the bearing hole 11 by each cutter 63 is conducted.

During this boring operation a cutting oil i9 being supplied into a space b~tween the inner sleeve 162 press fit in the bearing member 82 in the support ~ig 8 and the boring bar 7 and hence, even if the boring bar 7 is rotated at a higher speed, seizure can not occur, thus making it possible to conduct hlgher accuracy boring while maintaining the axial center of the boring bar 7 with a higher precision.

In addition, since the boring bar 7 is suspended for pivotal movement in all directions, even if the axis of the bearing hole 11 in the work plece W at the working station S is not completely vertical, such displacement can be absorbed to accurately afect the boring.

When the boring is completed, the stop position switch-over cylinder 127 is operated again to expand. This causes the movin~ stand 125 to be retracted several mm away from the post 3 and the axis of the bearing hole 11 to be offset from the axis of the boring bar 7. In this state, the boring bar 7 is raised, wherein each cutter 63 can not come into contact with the bearing hole 11 and hence, produces any scratches such as cutter marks in the bearing hole 11. Thereafter, the urging cylinder 12~ is contracted to retract the pallet holding frame 111 to the posi-tion of the transfer mechanism 10 and further, the clamp cylinder 136 is contracted to release the pallet 111 clamped on the pallet holding frame 130, and the pallet 111 is then transferred out of the working statlon S by the transfer mechanism 10.
~0 In this manner, the boring of the work piece W is completed. With a work piece W cha~ged in type, -the boring bar 7 and support jig 8 varying in type depending on the type of the work piece W can be disposed in a position at the working station S, as required.

More particularly, the index motor 43 of the index mechanism 42 may be actuated to move a tool head 6 having a desired boring bar 7 supported thereon to a position at the working station S, so that such tool head 6 can be fixed to the drive mechanism 4 by the clamp cylinder 57. In addition, the index motor 70 of the index mechanism 69 may be actuated to move a desirsd support ~ig 8 to a position at the working station S, and the operation of the clamp cylinders 96 and 97 enables such support jig 8 to be fixedly located at the working station S.
Therefore, the boring bar 7 and the support ~ig 8 can be easily ~s~a~

and rapidly replaced by another depending on the variation in type of work piece W to provide for the production of a variety of artlcles in a small quantity.

In the work support mechanism 9, the reverse motor 128 ls mounted to provide for the reverse of a work pisce W in the event when the work piece w is sub~ected to the slicing of its end surface in addition to the boring and thereEore, it can be dispensed with when only the boring is intended to be carried out.

.

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for boring a workpiece having a plurality of axially spaced holes which are to be bored over a relatively great distance In the axial direction of the workpiece, compris-ing the steps of suspending for universal pivotal movement a bor-ing bar which has a plurality of cutters provided thereon at axi-ally spaced positions and extending radially eccentrically at one side of the bar, said cutters being adapted for boring a plural-ity of holes in a workpiece provided on a common axis at axially spaced positions; bringing and locating the workpiece to a posi-tion below the boring bar with the axis of said holes being ver-tical and transversely offset from the axis of the boring bar and then lowering said boring bar while holding the offset location of the bar relative to the holes to pass the boring bar through the holes in the workpiece, so as to avoid contact of the cutters on the bar with the holes, slidably and rotatably supporting the boring bar at least at two points thereof axially spaced apart from each other, aligning the axis of the boring bar and the axis of the holes in the workpiece by transversely displacing the workpiece relative to the boring bar; and effecting boring of said holes by providing relative rotation and axial movement between the boring bar and the workpiece and the axis of the bor-ing bar remaining aligned with the axis of the workpiece.

2. A process as claimed in claim 1, wherein the axis of the boring bar and the axis of the holes in the workpiece are aligned before boring by transversely moving the workpiece rela-tive to the bar.

3. A process as claimed in claim 2, wherein the align-ing of the axis of the boring bar and the axis of the holes in the workpiece is effected while the workpiece remains rotatably and slidably supported at said at least two points.

4. A process as claimed in claim 1, wherein said axial holes in the workpiece are formed in axially spaced bearing por-tions of the workpiece, said boring bar being lowered eccentri-cally through the workpiece until each cutter is brought to a position axially slightly offset from the hole in the respective bearing portion which it is to bore whereafter when the axis of the boring bar and the axis of the hole are aligned, the cutters will be in operative position to bore the holes in the bearing portions when relative rotation and axial movement is provided between the boring bar and the workpiece.

5. A process as claimed in claim 4, comprising eccen-trically positioning the boring bar and the workpiece after the boring operation and raising the boring bar from the holes in the workpiece in eccentric relation to avoid contact of the cutters with the bored holes.

6. A process as claimed in claim 1, wherein the boring bar is supported at one of said points by a support tube in a support member, said support tube moving axially in said support member during axial insertion of the boring bar into the work-piece, said support tube having a released position for loose insertion of the boring bar into the hole and an engaged position when the boring bar bores the holes in the workpiece, said sup-port tube and support member undergoing relative angular movement when going between said released and engaged positions during relative axial travel of the boring bar prior to the boring of said holes.

7. A process as claimed in claim 6, comprising resillently and tightly engaging the boring bar in a slidable and rotatable bearing at one of said other points at which the bar is slidably and rotatably supported when the boring bar has been passed through the hole.

8. An apparatus for boring a plurality of axially spaced holes in a workpiece over a relative great distance in the axial direction of the workpiece, comprising a vertical post; a tool head movably supported on said post around the circumference thereof and including a vertical rotary shaft; a boring bar hav-ing an upper end and provided with a plurality of cutters extend-ing radially and eccentrically at one side of the bar at axially spaced positions thereon; a universal joint connecting the upper end of the boring bar to the rotary shaft to suspend the boring bar from the tool head for universal pivotal movement; a support jig including at least two bearing portions disposed on said post for slidably and rotatably supporting said boring bar; and means for supporting the workpiece for selective positioning of the holes in the workpiece with respect to the boring bar between eccentric and concentric positions, said support means being operable to hold the workpiece in the eccentric position relative to the bar, when the bar is passed through the holes in the work-piece in order to avoid contact of the cutters with the holes and to hold the workpiece in the concentric position relative to the bar during the boring operation.

9. An apparatus as claimed in claim 8, comprising a drive mechanism including a rotary drive motor liftably disposed on said post, a lift mechanism on said post for lifting said drive mechanism on said post, said vertical rotary shaft being connectable to said rotary drive motor and detachably connected to said drive mechanism, a jig carrier for supporting a plurality of support jigs around said post, means supporting said jig car-rier for rotation about a vertical axis of the post, and an index mechanism connected to the jig carrier for angularly moving a desired support jig to a position below the boring bar.

10. An apparatus as claimed in claim 9, comprising a plurality of said tool heads arranged around said post, a head carrier supporting said tool heads and disposed for rotation around said post, and another index mechanism connected to the head carrier to angularly displace a desired tool head to a posi-tion at said drive mechanism.

11. An apparatus for boring a workpiece according to claim 10, wherein said support means includes a movable stand including a holding frame for detachably holding a pallet for supporting and fixing the workpiece and being movable to a posi-tion below the boring bar, and a stop position switch-over cylin-der positioned to restrict the movement of the movable stand in two steps and including a rod for abutting against the movable stand in two positions, on one of said positions the axis of the holes in the workpiece being displaced from the axis of the bor-ing bar to assume said eccentric position and in the other of said positions the axis of the holes being aligned with the bor-ing bar to assume said concentric position thereby to enable the boring bar to be inserted through said holes.

12. An apparatus as claimed in claim 11, comprising a generally regular polygonal support tube fitted on said boring bar and having an external surface with plurality of apices and a circularly arcuate slide surface at each apex, and a support mem-ber fixedly mounted on one of said bearing portions of said sup-port jig, said support member having a generally circular support hole with an internal diameter corresponding to that of said slide surface, and axially extending escape grooves at circumfer-entially regular spaced intervals in the same number as said slide surfaces, said support tube being insertable into said sup-port member, and guide means between said support member and said support tube for angularly displacing said support tube relative to said support member to cause each slide surface facing a cor-responding escape groove to come into sliding contact with an inner surface of said support hole when the support tube advances a given distance after the start of insertion thereof into said support member.

13. An apparatus for boring a hole in a workpiece over a relative great distance in the axial direction, comprising a vertical post; a tool head movably supported on said post and including a vertical rotary shaft; a boring bar having an upper end; a universal joint connecting the upper end of the boring bar to the rotary shaft to suspend the boring bar from the tool head for universal pivotal movement; a support jig including at least two bearing portions disposed on said post for slidably and rotatably, supporting said boring bar; and support means for sup-porting the workpiece for selective positioning of the hole in the workpiece with respect to the boring bar between eccentric and concentric positions; said support means including a movable stand including a holding frame for detachably holding a pallet for supporting and fixing the workpiece and being movable to a position below the boring bar, and stop position switch-over cylinder positioned to restrict the movement of the moving stand in two steps and including a rod for abutting against the moving stand in two positions, in one of said positions the axis of the hole in the workpiece being displaced from the axis of the boring bar to assume said eccentric position and in the other of said positions the axis of the hole being aligned with the axis of the boring bar to assume said concentric position thereby to enable the boring bar to be inserted through said hole.

14. An apparatus for boring a hole in a workpiece over a relative great distance in the axial direction, comprising a vertical post; a tool head movably supported on said post and including a vertical rotary shaft; a boring bar having an upper end; a universal joint connecting the upper end of the boring bar to the rotary shaft to suspend the boring bar from the tool head for universal pivotal movement; a support jig including at least two bearing portions disposed on said post for slidably and rotatably supporting said boring bar; support means for support-ing the workpiece for selective positioning of the hole in the workpiece with respect to the boring bar between eccentric and concentric positions; a generally regular polygonal support tube fitted on said boring bar and having an external surface with plurality of apices and a circularly arcuate slide surface at each apex; a support member fixedly mounted on one of said bear-ing portions of said support jig, said support member having a generally circular support hole with an internal diameter corre-sponding to that of said slide surface, and axially extending escape grooves at circumferentially regular spaced intervals in the same number as said slide surfaces, said support tube being insertable into said support member; and guide means between said support member and said support tube for angularly displacing said support tube relative to said support member to cause each slide surface facing a corresponding escape groove to come into sliding contact with an inner surface of said support hole when the support tube advances a given distance after the start of insertion thereof into said support member.

15. A process for boring a workpiece disposed at a working station located adjacent the lower portion of a vertical support post, said post having a substantially cylindrical con-figuration and being provided with a plurality of working tools around the outer periphery of the post, said tools being spaced from each other and movable circumferentially of the post such that a desired one of the tools can be moved to a position above the workpiece of the working station and lowered to bore the workpiece, said process comprising the steps of providing the workpiece with a plurality of holes to be bored on a common axis at axially spaced positions over a relatively long distance; ver-tically suspending a boring bar as said tool for universal move-ment at the working station, said boring bar having a plurality of cutters thereon at axially spaced positions projecting in a radial direction at one side of the bar; bringing and locating the workpiece to a position below the boring bar with the axis of said holes being vertical and radially offset from the axis of the boring bar and then lowering said boring bar while maintain-ing the offset location of the bar relative to the holes to pass the boring bar through the holes in the workpiece without contact of the cutters on the bar with the holes, and rotatably support-ing the boring bar at least at two points axially spaced apart from each other; and displacing the workpiece relative to the boring bar to align the axis of the boring bar and the axis of the holes in the workpiece and effecting boring of said holes while rotating said bar around its axis.

16. An apparatus for boring a plurality of axially spaced holes in a workpiece over a relatively great distance in the axial direction thereof, said apparatus comprising a vertical support post; a plurality of tool heads having respective axes of rotation and movably supported on said post at circumferentially spaced positions, said tool heads being selectively movable to a working station located adjacent the post and being capable of ascending and descending movements at said working station; a plurality of boring bars constituting working tools vertically suspended from respective toolheads for universal movement, said boring bars each including a plurality of cutters thereon at axi-ally spaced positions projecting radially at one side of the bor-ing bar; a universal joint for each boring bar connecting an upper end of the boring bar to a vertical rotary shaft of the tool head to suspend the bar for said universal movement; a sup-port jig including at least two bearing portions disposed on said post at the working station for slidably and rotatably supporting the boring bar at the working station; and support means for sup-porting a workpiece, which has a plurality of holes to be bored on a common axis and at axially spaced positions over a rela-tively great distance, for selective positioning of the holes in the workpiece with respect to the boring bar between eccentric and concentric positions relative to the axis of the boring bar;
said support means including means for holding the workpiece in the eccentric position relative to the bar, when the bar is passed through the holes in the workpiece at said working sta-tion, in order to avoid contact of the cutters with the holes and for holding the workpiece in the concentric position relative to the bar during the boring operation.